Exhibit 4.1

                   Restated Certificate of Incorporation
                                     Of
                      Clean Diesel Technologies, Inc.

     The original certificate of incorporation of Clean Diesel
Technologies, Inc. (the "corporation") was filed with the Secretary of
State of Delaware on January 19, 1994. This restated certificate of
incorporation of the corporation was duly adopted by the vote of the Board
of Directors of the corporation in accordance with Section 245 of the
Delaware General Corporation Law on June 18, 2004 without a vote of
shareholders. This restated certificate of incorporation only restates and
integrates and does not further amend the provisions of the corporation's
certificate of incorporation as theretofore amended and supplemented and
there is no discrepancy between those provisions and the provisions of this
restated certificate.

1.   The name of the corporation is

             Clean Diesel Technologies, Inc.

2.   The  address  of its  registered  office in the State of  Delaware  is
     Corporation  Trust  Center,   1209  Orange  Street,  in  the  city  of
     Wilmington,  County of New Castle. The name of its registered agent at
     such address is The Corporation Trust Company.

3.   The nature of the  business or purpose to be  conducted or promoted is
     to engage in any lawful act or activity for which  corporations may be
     organized under the General Corporation law of Delaware.

4.   The  corporation  shall have  authority  to issue the total  number of
     Thirty  Million One Hundred  Thousand  (30,100,000)  shares of the par
     value of $0.05 per share,  amounting  in the  aggregate to One Million
     Five Hundred and Five Dollars ($1,505,000),  and of such shares Thirty
     Million  (30,000,000)  shall be  designated  as  common  stock and One
     Hundred Thousand (100,000) shall be designated as preferred stock.

     The  preferred  stock may be  issued  from time to time in one or more
     series.  The Board of  Directors  is  hereby  authorized,  within  the
     limitations and restrictions set forth in this  Certificate,  to issue
     the preferred  stock in one or more series and, in connection with the
     creation of any such series,  by resolution or  resolutions  providing
     for the issue of the shares thereof,  to determine and fix such voting
     powers,  full or limited,  or no voting powers, and such designations,
     preferences  and  relative,  participating,  optional or other special
     rights  and  qualifications,   limitations  or  restrictions  thereof,
     including  without  limitation,   dividend  rights,   dividend  rates,
     conversion rights,  rights and terms of redemption  (including sinking
     fund  provisions),  and the  liquidation  preferences  of any unissued
     series of preferred  stock and the number of shares  constituting  any
     such  series;  and to increase or decrease the number of shares of any
     series subsequent to the issue of shares of that series, but not above
     the total number of  authorized  shares of the class and not below the
     number of shares of such series then  outstanding.  In case the number
     of shares of any series shall be so decreased, the shares constituting
     such  decrease  shall  resume the  status  which they had prior to the
     adoption of the resolution  originally  fixing the number of shares of
     such series.  In no event,  however,  may the Board of Directors issue
     preferred  stock which has the effect of voting as a class  during the
     pendency  of a tender  offer to  purchase  more than 50% of the common
     stock of the  Company,  unless the tender  offeror(s)  consent to such
     issuance.

5.   In  furtherance  and not in  limitation  of the  powers  conferred  by
     statute, the Board of Directors is expressly authorized to make, alter
     or repeal the by-laws of the corporation.

6.   Elections  of  Directors  need not be by  written  ballot  unless  the
     by-laws of the corporation shall so provide.

7.   Meetings  of  stockholders  may be held within or without the state of
     Delaware, as the by-laws may provide. The books of the corporation may
     be kept  outside of the State of  Delaware  at such place or places as
     may be designed  from time to time by the board of directors or in the
     by-laws of the corporation.

8.   (a) A director of the  corporation  shall not be personally  liable to
     the corporation or its stockholders for monetary damages for breach of
     fiduciary  duty as a  director  except  that this  Article 8 shall not
     eliminate  or limit a director's  liability  (i) for any breach of the
     director's  duty of loyalty to the  corporation  or its  stockholders,
     (ii)  for  acts  or  omissions  not in good  faith  or  which  involve
     intentional  misconduct  or a knowing  violation  of law,  (iii) under
     Section 174 of the Delaware  General  Corporation law, or (iv) for any
     transaction  from  which the  director  derived an  improper  personal
     benefit.

     (b) If the Delaware General  Corporation Law is amended after approval
     by the  stockholders of this Article 8 to authorize  corporate  action
     further  eliminating or limiting the personal  liability of directors,
     then  the  liability  of  a  director  of  the  corporation  shall  be
     eliminated or limited to the fullest extent  permitted by the Delaware
     General Corporation Law, as so amended from time to time.

     (c) Any repeal or  modification  of this  Article 8 shall not increase
     the personal liability of any director of this corporation for any act
     or occurrence  taking place prior to such repeal or  modification,  or
     otherwise adversely affecting any right or protection of a director of
     the corporation existing at the time of such repeal or modification.

9.   (a) Except as otherwise provided below, the corporation, shall, to the
     fullest  extent  indemnify  each person who is, or shall have been,  a
     director,  officer,  employee or agent of the corporation or who is or
     was a director,  officer,  employee or agent of the corporation and is
     serving, or shall have served, at the request of the corporation, as a
     director, officer, employee or agent of another organization or in any
     capacity with respect to any employee benefit plan of the corporation,
     against all  liabilities  and expenses  (including  judgments,  fines,
     penalties,  amounts paid or to be paid in  settlement,  and reasonable
     attorneys  fees)  imposed  upon or  incurred  by any such  person (the
     "Indemnitee")  in  connection  with, or arising out of, the defense of
     disposition of any action, suit or other proceeding,  whether civil or
     criminal,  in  which  he may be a  defendant  or with  which he may be
     threatened or otherwise involved, directly or indirectly, by reason of
     his being or having been such a director,  officer,  employee or agent
     or as a result of his  serving or having  served  with  respect to any
     such employee benefit plan;  provided,  however,  that the corporation
     shall  provide  no  indemnification  with  respect to any matter as to
     which any such Indemnitee shall be finally  adjudicated in such action
     suit or proceeding  not to have acted in good faith in the  reasonable
     belief  that  his  action  was  (i)  in  the  best  interests  of  the
     corporation  or (ii) to the extent such matter relates to service with
     respect to an employee  benefit  plan,  in the best  interests  of the
     participants or beneficiaries of such employee benefit plan.

     (b) The right to  indemnification  conferred  in this  Article 9 shall
     include the right to be paid by the  corporation  for  liabilities and
     expenses  incurred in connection  with the settlement of compromise of
     any such action, suite or proceeding,  pursuant to a consent decree or
     otherwise, unless a determination is made, within forty-five (45) days
     after  receipt  by  the  corporation  of  a  written  request  by  the
     Indemnitee for indemnification,  that such settlement or compromise is
     not in the best  interests of the  corporation  or, to the extent such
     matter  related to service with respect to an employee  benefit  plan,
     that such settlement or compromise is not in the best interests of the
     participants  or  beneficiaries  of such plan. Any such  determination
     shall be made (i) by the board of  directors of the  corporation  by a
     majority vote of a quorum  consisting of disinterested  directors,  or
     (ii)  if  such  quorum  is  not  obtainable,  by  a  majority  of  the
     disinterested directors then in office. Notwithstanding the foregoing,
     if there are less than two disinterested  directors of the corporation
     then in office,  the board of  directors  shall  promptly  direct that
     independent  legal  counsel (who may be regular  legal  counsel to the
     corporation)  determine,  based on facts know to such  counsel at such
     time,  whether such  Indemnitee  acted in good faith in the reasonable
     belief that this action was in the best  interests of the  corporation
     or the  participants  or  beneficiaries  of any such employee  benefit
     plan, as the case may be; and, in such event, indemnification shall be
     made to such  Indemnitee  unless,  within  forty-five  (45) days after
     receipt  by the  corporation  of the  request by such  Indemnitee  for
     indemnification,  such independent  legal counsel in a written opinion
     to the corporation determines that such Indemnitee did not act in good
     faith  in the  reasonable  belief  that  his  action  was in the  best
     interests of the corporation or the  participants or  beneficiaries of
     any such employee benefit plan, as the case may be.

     (c) As a  condition  precedent  to his  right to be  indemnified,  the
     Indemnitee  must give the  corporation  notice in  writing  as soon as
     practicable of any action, suit or proceeding  involving him for which
     indemnity will or could be sought. With respect to any action, suit or
     proceeding of which the corporation is notified,  the corporation will
     be entitled to participate therein at its own expense and/or to assume
     the defense thereof at its own expense,  with legal counsel reasonably
     acceptable to such  Indemnitee.  After notice from the  corporation to
     the  Indemnitee  of  its  election  so to  assume  such  defense,  the
     corporation  shall not be liable to such  Indemnitee  for any legal or
     other expenses  subsequently incurred by such Indemnitee in connection
     with such  claim,  but the fees and expense of such  counsel  incurred
     after notice from the  corporation  of its  assumption  of the defense
     thereof  shall be at the  expense  of the  Indemnitee  unless  (i) the
     employment  of counsel by the  Indemnitee  has been  authorized by the
     corporation,  (ii)  counsel to the  Indemnitee  shall have  reasonably
     concluded  that there may be a conflict of interest or position on any
     significant  issue between the  corporation  and the Indemnitee in the
     conduct of the defense of such action or (iii) the  corporation  shall
     not in fact have  employed  counsel  to  assume  the  defense  of such
     action,  in each of which cases,  the fees and expenses of counsel for
     the Indemnitee shall be at the expense of the  corporation,  except as
     otherwise  expressly  provided by this Article.  The corporation shall
     not be entitled  to assume the  defense of any claim  brought by or on
     behalf of the  corporation  or as to which counsel for the  Indemnitee
     shall have reasonably made the conclusion provided for in (ii) above.

     (d)  Subject  to  paragraph  (c) above,  the right to  indemnification
     referred to in this Article  shall include the right to be paid by the
     corporation  for  expenses  (including   reasonable  attorneys'  fees)
     incurred in defending a civil or criminal  action,  suit or proceeding
     in  advance  of  its  final  disposition,  subject  to  receipt  of an
     undertaking  by  the  Indemnitee  to  repay  such  payment  if  it  is
     ultimately   determined   that  the  Indemnitee  is  not  entitled  to
     indemnification  under this Article.  Such undertaking may be accepted
     without  reference to the financial ability of such Indemnitee to make
     such  repayment.  Notwithstanding  the foregoing,  no advance shall be
     made by the corporation under this paragraph (d) if a determination is
     reasonably  and promptly  made by the board of directors by a majority
     vote of a quorum  consisting  of  disinterested  directors or, if such
     quorum is not obtainable, by a majority of the disinterested directors
     of the  corporation  then in office  or, if there are not at least two
     disinterested  directors then in office,  by independent legal counsel
     (who may be  regular  legal  counsel  to the  corporation)  in written
     opinion  that,  based on  facts  known to the  board of  directors  or
     counsel at such time, such Indemnitee did not act in good faith in the
     reasonable  belief  that his action was in the best  interests  of the
     corporation  or  the  participants  or  beneficiaries  of an  employee
     benefit plan of the corporation, as the case my be.

     (e) If an Indemnitee  is entitled  under any provision of this Article
     to  indemnification  by the  corporation  of some or a portion  of the
     liabilities or expenses imposed upon or incurred by such Indemnitee in
     the investigation,  defense, appeal or settlement of any action, suite
     or proceeding  but not,  however,  for the total amount  thereof,  the
     corporation  shall  nevertheless  indemnify  the  Indemnitee  for  the
     portion of such  liabilities  or expenses to which such  Indemnitee is
     entitled.

     (f) The right to indemnification  and the payment of expenses incurred
     in defending  any action,  suit or  proceeding in advance of its final
     disposition  conferred in this  Article  shall not be exclusive of any
     other right which any person may have or thereafter  acquire under any
     statute,   provision  of  the  articles  of  incorporation,   by-laws,
     agreement,  vote of stockholders  of managing  directors or otherwise.
     Without  limiting the  generality of the foregoing,  the  corporation,
     acting through its board of directors,  may enter into agreements with
     any   director   or  employee  of  the   corporation   providing   for
     indemnification   rights   equivalent   to   or   greater   than   the
     indemnification rights set forth in this Article.

     (g) The  corporation  may  purchase  and  maintain  insurance,  at its
     expense,  to  protect  itself  and any  director  or  employee  of the
     corporation or another  organization or employee  benefit plan against
     any  expense or  liability  incurred by him in any such  capacity,  or
     arising out of the status as such.

     (h) The corporation's obligation to provide indemnification under this
     Article  shall  be  offset  to the  extent  of  any  other  source  of
     indemnification or any otherwise applicable insurance coverage under a
     policy maintained by the corporation or any other person.

     (i) Without the  consent of a person  entitled to the  indemnification
     and other rights provided in this Article,  no amendment  modifying or
     terminating  such rights shall  adversely  affect such person's rights
     under this Article with respect to the period prior to such amendment.

     (j) If this Article or any portion thereof shall be invalidated on any
     ground by any court of competent  jurisdiction,  then the  corporation
     shall nevertheless indemnify each Indemnitee as to any liabilities and
     expenses with  respect to any action,  suit or proceedings to the full
     extent permitted by any applicable  portion of this Article that shall
     not  have  been  invalidated  and  to the  full  extent  permitted  by
     applicable law.

     (k) As used in this Article,  the term "director" "officer" "employee"
     "agent"  and  "person"  include  their  respective  heirs,  executors,
     administrators and legal  representatives and an "interested" director
     is one against whom in such  capacity the  proceedings  in question or
     another proceeding on the same or similar grounds is then pending.

10.  The corporation  reserves the right to amend,  alter, change or repeal
     any provision  contained in this certificate of incorporation,  in the
     manner  now  or  hereafter  prescribed  by  statute,  and  all  rights
     conferred  upon  stockholders  herein  are  granted  subject  to  this
     reservation.


     THE UNDERSIGNED duly authorized officer of the corporation does hereby
set his hand this 18th day of June 2004.

                                    /s/ C.W. Grinnell
                                    -------------------------
                                      Charles W. Grinnell
                                          Vice President and Secretary